The present invention relates to an improved combination plastic and metal threshold construction which retards thermal conductivity of heat out of a home or building.
The instant invention particularly relates to thresholds for use in doorways having a door hinged therein.
Prior art thresholds as exemplified in U.S. Pat. No. 3,346,994 are formed of three extruded aluminum shapes and a strip of insulating material, with two of the shapes being interlocked and defining that part of the threshold outwardly of the bottom of a door and which is exposed to outside temperatures. The third shape or base plate is mechanically interlocked with the insulating material which is in turn interlocked with the first two shapes, with the third shape extending inwardly from the door thermally insulated from the first two. A strip of resilient insulating material is also carried by the bottom edge of the door in position to sealingly engage the threshold. The present invention has a number of advantages over such prior art thresholds.
The present invention provides a threshold which can be manufactured with considerably less production costs and time. With the instant invention, all assembly time is eliminated.
Additionally, the present invention provides a threshold that can be readily replaced when damaged.
An important object of the present invention is to provide a complete thermal barrier as opposed to a thermal "break" as exemplified in the prior art construction.